706
FXUS63 KMQT 170014
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
814 PM EDT Fri May 16 2025

.KEY MESSAGES...

- Thunderstorms this afternoon may be capable of producing
  damaging winds and large hail across central Upper Michigan.

- Dry period expected to begin Sunday and linger through at
  least Wednesday. High temperatures in this period are expected
  mostly in the 50s to low 60s each day.

&&

.SHORT TERM /THROUGH TODAY/...
Issued at 133 PM EDT Fri May 16 2025

This morning we found ourselves caught within the dry sector of a
surface low spinning just upstream in Minnesota. This provided Upper
Michigan with clear skies through the morning, with some clouds
beginning to push into the west and some cumulus development near
noon EDT. Temperatures in this window have warmed into the 70s while
mixing has allowed for gusty winds near 30 mph to mix to the surface
here and there, alongside drier air aloft. Minimum RH values so far
have fallen into the 30s.

Current SPC Mesoanalysis pings the region with ~500-1500 j/kg SBCAPE
alongside effective bulk shear of 30-50kts. With continued
destabilization expected across central Upper Michigan this
afternoon, showers and thunderstorms may develop as synoptic support
helps provide a window for additional lift. CAMS are in relatively
good agreement that thunderstorm initiation could begin between 4-
6pm this afternoon central, then shift eastward into the evening
hours. Model soundings show very good mixing into a core of 50-60kts
aloft, DCAPE between 500-1000j/kg, and steep mid-level lapse rates
that support a window with a damaging wind and large hail risk with
any storms that develop. Greatest risk area appears to be the middle
third of Upper Michigan.

Outside of this risk, strong southerly winds across the area may
become more widespread and increase to ~40mph given the increased
mixing that`s expected this afternoon. However, given that we appear
to be underperforming the higher end guidance packages at the
moment, I don`t yet see a need for a wind headline. Will continue to
monitor the higher wind threat for the time being though.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 220 PM EDT Fri May 16 2025

Upper level low traversing the area tonight will continue to shift
east through the Great Lakes this weekend while mid-level ridging
shifts east through middle America. At the surface, low pressure
will also progress eastward tonight then exit into Ontario by
Saturday afternoon followed by a high moving into Hudson and James
Bay. This transition will allow any showers and thunderstorms that
develop this afternoon/evening to end tonight for our forecast area,
then wrap around showers to press downwind into Upper Michigan`s
north through the day Saturday while a cooler airmass pours into the
area. By afternoon, areas in the south-central should begin drying
out. Sunday, showers should begin to diminish in the north as the
effects of the ridging over the region becomes more dominant. Dry
conditions look to hold fast over the area into at least the middle
of next week, at which point a shortwave dropping southeast just
east of Lake Superior Monday night begins to slowly phase with an
upper level low pressing eastward through the mid-Mississippi River
Valley. By Wednesday night/Thursday, the resultant upper level low
may provide enough synoptic support for another round of rain.
Confidence is low though given the uncertainty in this feature and
it`s surface reflection`s position.

Temperatures will slide this weekend as the cooler airmass from the
north expands into the Upper Great Lakes. Highs Saturday in the 50s
to low 60s will feel warm compared to Sunday`s widespread 40s. We
should warm afterwards back into 50s to low 60s for most of the
coming week. Overnight lows will follow the same trend; expect 40s
tonight with 30s afterwards, save near 40 by the lakeshores. Some
high 20s can`t be ruled out in the interior west half Sunday and
Monday nights. The effect of the dry air, temperatures, and daytime
mixing next Monday-Wednesday should be enough to support afternoon
RH values falling into the 30s and 20s, potentially into the teens,
in interior locations while gusty northeasterly winds near 20 mph
mix down to the surface.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 814 PM EDT Fri May 16 2025

Some additional tsra are likely to impact SAW in the next two hours,
otherwise periods of shra are expected at all sites into Sat. Expect
all sites to fall to MVFR/IFR into tonight, continuing into Sat.

&&

.MARINE...
Issued at 220 PM EDT Fri May 16 2025

Low pressure will gradually shift east through Lake Superior through
Saturday. Ahead of the low this afternoon/evening, strong low level
jet will be capable of producing winds near 30kts. There is some
gale potential, but the increasing low level temperature profile
over the lake this afternoon will create greater stability and make
it difficult for these strong winds to mix down to the surface. That
being said though, showers and thunderstorms that develop later this
afternoon/evening could provide enough extra support for isolated
pockets of stronger winds over eastern Lake Superior, particiarly if
a stronger storm develops. If a strong storm gets organized, 50+
knot winds will be possible.

Winds shift to the northwest Saturday afternoon/evening in the lee
of the low, allowing for a period of cold air advection. This looks
to create another opportunity for near 30kt winds, but the profile
isn`t expected to be cold enough for significant lake-induced
instability, so gale potential is low (<25%). Winds look to lighten
through the day Sunday, falling back below 20kts lake-wide by
afternoon. Tighther pressure gradient looks to develop Monday and
Tuesday, mainly in western Lake Superior thanks to a high shifting
through Hudson Bay and a low moving east into the middle-Mississippi
River Valley. This may produce northeast winds near 30kts going down
into Duluth Harbor.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...JTP
LONG TERM...JTP
AVIATION...Jablonski
MARINE...JTP